Neural precursor cells tune striatal connectivity through the release of IGFBPL1

The adult brain retains over life endogenous neural stem/precursor cells (eNPCs) within the subventricular zone (SVZ). Whether or not these cells exert physiological functions is still unclear. In the present work, we provide evidence that SVZ-eNPCs tune structural, electrophysiological, and behavioural aspects of striatal function via secretion of insulin-like growth factor binding protein-like 1 (IGFBPL1). In mice, selective ablation of SVZ-eNPCs or selective abrogation of IGFBPL1 determined an impairment of striatal medium spiny neuron morphology, a higher failure rate in GABAergic transmission mediated by fast-spiking interneurons, and striatum-related behavioural dysfunctions. We also found IGFBPL1 expression in the human SVZ, foetal and induced-pluripotent stem cell-derived NPCs. Finally, we found a significant correlation between SVZ damage, reduction of striatum volume, and impairment of information processing speed in neurological patients. Our results highlight the physiological role of adult SVZ-eNPCs in supporting cognitive functions by regulating striatal neuronal activity.


March 2021
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-Local field potential's epochs were visually examined and power spectra of artefact-free segments were computed using fast Fourier transforms by using the commercial software NeuroExplorer (Plexon).
-The data that support the findings of this study are available in the Souce data file and more information could give from the corresponding author on reasonable request.
-The gene-sets included in the GSEA analyses were obtained from Canonical Pathways, Hallmark and the Gene Ontology (GO) collections as they are reported in the MSigDB database (https://www.gsea-msigdb.org/gsea/msigdb/index.jsp). The accession number for these data is GSE165815. We provide a temporary token for editor and reviewers to access the data: gjqbgmespvwhrof. The data will become accessible to readers at the time of the online publication. -For behavioural experiments to establish the sample size we used the G-power v3.1.9.4 (Heinrich-Heine-Universität Düsseldorf) with Oneway Anova statistical test, with 80% of power and 5% of alpha error. From the analysis we obtained n=12 mice for group.
-For determining on immunostainings and the ablation efficacy we used n=4-5 sections for each mouse, n=3 mice for each group; this sample size is sufficient given the effect of the treatment and preliminary experiments and previous publications; -For Golgi staining and Sholl analysis we traced and measured n=6-8 neurons for each mouse, n= 6 mice per group analysing; this sample size is sufficient given the effect of the treatment and preliminary experiments; -For electrophysiological experiments we recorded cells or pairs, n=15-20 per group, with n=3-5 mice per group. We based these sample sizes on the experience and the literature.
-For gene expression analysis and RNA-seq we analysed n=5 mice per group. This sample size is sufficient given the effect of the treatment and preliminary experiments and previous publications; -For human MRI we examined n=97 MS patients (mean age 36.8 ± 7.56 years, female/male [F/M] =55/42, median EDSS 2.0, median disease duration 5.0 years) and 43 age-and sex-matched healthy controls (HC, 34.8 ± 6.52 years, F/M=19/24). This sample size is sufficient considering the literature data.
In our experiments no sample size calculation was performed using statistical software; we decided the sample size on our experience and following our same experiments done in the past and published.
No data were excluded.
We repeated the mouse immunostainings for 3 times and we observed a strong reproducibility. Golgi staining, behavioural test, RNAseq and study of local field potential were performed once.

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In our experiments we used transgenic mice that were allocated randomly to the treatment group; different transgenic groups/ treatments were randomly distributed within cages reducing possible biases; we used both female and male mice which a similar age and allocated them randomly to the treatment group. During experiments analysis was performed randomly between treatment groups. For behaviuoral experiments we used male mice.
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Behavioral performance measures All cells used were tested for Mycoplasma by PCR and we confirmed that all cells are negative.
Used cell lines are not present in the ICLAC register.
Adult female and male C57Bl/6 (6-8 weeks old) and transgenic mice were purchased from Charles River or generated in our animal facility in SPF conditions. The animals were housed in Ventilated Cages. The mice were kept in 12hour/12hour light/dark cycles, at 21.5°C +/-1.5°C temperature and 55% +/-15 humidity.
the study didn't involve wild animals.
the study didn't involve animals collected from the field. MS patients were recruited among those regularly followed-up at the MS Center of the San Raffaele Scientific Institute, Milan (Italy). Specifically, at the time of the neurological follow-up, the neurologist systematically asked to patients if they were interested into undergoing an experimental MRI protocol, with no contrast administration, for research purposes. HC were recruited among health care professionals, students, and their acquaintances, therefore, there might have been a selection bias towards higher educational levels. However, since the neuropsychological performance of HC was not analyzed in this paper, this should not have affected the results.
-MRI study in humans was approved by the Ethical Committee of the San Raffaele Scientific Institute, Milan (Italy), and written informed consent was obtained from all participants at the time of data acquisition.
-permission to use human foetal CNS tissue was granted by the ethical committee of the San Raffaele Hospital (approval on 09/06/2016). Tissue procurement was in accordance with the declaration of Helsinki and in agreement with the ethical guidelines of the European Network for Transplantation (NECTAR).
-permission to generate induced-pluripotent stem cells ( Retrospective evaluation of brain MRI scans acquired from 97 patients with multiple sclerosis (MS) and 43 age-and sexmatched healthy controls (HC). MRI scans were obtained with a standardized protocol in a single session.
Lesion volume on FLAIR, brain volumes (whole brain, grey matter, white matter and deep grey matter nuclei), cortical thickness, fractional anisotropy and mean diffusivity. Lesion volume and microstructural damage (fractional anisotropy and mean diffusivity) were also assessed within a in-home made mask of the subventricular zone, designed according to anatomical references. Data are presented as mean (standard deviation) or median (interquartile range), according to normality assumption. Brain volumes were normalized according to head-size by the scaling factor obtained from the SIENAX (V-scaling).
No normalization template was used. The mask of the subventricular zone was designed according to anatomical references (Cherubini et al., Neurosciences Letters 2010) in the Montreal Neurological Institute (MNI) space and registered on native 3D T1-weighted and diffusion-weighted images from each subject.
Only MR images with good quality (no artifact movements) were analyzed. Diffusion-weighted images were corrected for offsesonance and eddy current induced distortions and movements using the Eddy tool in the FSL library.
We should have answered no to this question. Indeed we confirm that we did not apply any volume censoring, since all the post-processing steps aimed at producing volume measures were checked. The quality review was applied to the Freesurfer and FSL-sienax pipeline and to the phases to obtain the subventricular zone. Furthermore the presence of outliers was assessed before the statistical analysis without receiving any alert that could justify the use of a censoring threshold.
Age-, sex-and phenotypes-adjusted linear models, partial correlations and stepwise multiple linear regressions were used to assess the damage of the subventricular zone in patients and to identify predictors of caudate volume and cognitive scores (Symbol digit modalities test [SDMT] z-scores).
A mask of the subventricular zone was designed in the Montreal Neurological Institute (MNI) space based on the anatomical references described by Cherubini et al., Neurosciences Letters 2010.
This does not apply to the study since this is not a voxel-wise analysis.
We did not include any correction at this stage (i.e., imaging analysis), since this was not voxel-wise. Head-size normalized brain volumes were afterwards included in a canonical statistical analysis (i.e., linear models, partial correlations and stepwise multiple linear regression), adjusted for the major covariates (i.e., age, sex, and phenotypes).